How to Catch a Magnetic Monopole in the Act

A research team led by Foundry users has created a nanoscale “playground” on a chip that simulates the formation of exotic magnetic particles called monopoles. The study – published recently in Science Advances – could unlock the secrets to ever-smaller, more powerful memory devices, microelectronics, and next-generation hard drives that employ the power of magnetic spin to store data.

For years, other researchers have been trying to create a real-world model of a magnetic monopole – a theoretical magnetic, subatomic particle that has a single north or south pole. These elusive particles can be simulated and observed by manufacturing artificial spin ice materials – large arrays of nanomagnets that have structures analogous to water ice – wherein the arrangement of atoms isn’t perfectly symmetrical, leading to residual north or south poles.

Opposites attract in magnetism (north poles are drawn to south poles, and vice-versa) so these single poles attempt to move to find their perfect match. But because conventional artificial spin ices are 2D systems, the monopoles are highly confined, and are therefore not realistic representations of how magnetic monopoles behave.

The team used sophisticated lithography tools developed at the Foundry to pattern a 3D, square lattice of nanomagnets. Each magnet in the lattice is about the size of a bacterium and rests on a flat, 1-by-1-centimeter silicon wafer.

The chips were then studied at the ALS, a synchrotron light source research facility open to visiting scientists from around the world. The researchers used a technique called X-ray photoemission electron microscopy (PEEM), directing powerful beams of X-ray light sensitive to magnetic structures at the nanopatterns to observe how monopoles might form and move in response to changes in temperature.

The researchers now hope to pattern smaller and smaller nanomagnets for the advancement of smaller yet more powerful spintronics – a sought-after field of microelectronics that taps into particles’ magnetic spin properties to store more data in smaller devices such as magnetic hard drives.